The mounting of tools on an adapted interface of the motor device often requires the insertion of an intermediate part designed to limit the vibrations of the device and the tool in movement. In the case of a tool which functions in rotation, for example a cutting or drilling tool, vibrations can occur because of the resistance encountered by the cutting tool in contact with the material of the cut part. The radial vibrations interfere with the rotational movement of the cut part in relation to its axis of rotation. The intermediate damping system makes it possible to compensate for or cancel out radial vibrations which may be produced by the tool during rotation.
In general, the intermediate damping system is formed by a cylindrical part which forms a housing in which a cylindrical absorbent mass is arranged centred in the housing and held in position by elastic elements arranged on the periphery of the cylindrical mass, in contact with the internal wall of the cylindrical housing. The function of the absorbent mass is to vibrate in a phase offset to the cylindrical part of its housing and thus dampen radial vibrations generated by the cutting and in particular by the resistance encountered by the cutting tool. The damping/cylindrical mass assembly is then arranged to be aligned according to the axis of rotation of the machine and the tool. The various different elastic elements enable the damping of vibrational movements of the absorbent mass relative to the cylindrical part of the housing. The damping can be adjusted by modifying the elastic hardness of the elastic elements and by prestressing the latter. If the stiffness of the elastic elements/absorbent mass has not been adjusted, the cylindrical absorbent mass vibrates in a random manner and no longer performs its damping function.
An embodiment of an intermediate damping system integrating a prestressing mechanism is described in publication U.S. Pat. No. 6,443,673. In such a system, the absorbent mass is compressed between two elastomers in the cylindrical housing of the damping means by means of a clamping element. The clamping element forms part of the cylindrical housing of the damping means and forms a ramp for clamping elastomers mounted off-centre relative to the axis of the damping means. If such a device makes it possible to obtain a damping system in which the damping abilities can be adjusted, the device has the disadvantage of not being able to be integrated into existing cylindrical housing parts.
Document DE 1897206 proposes an alternative way of controlling the damping by using a mechanism for prestressing the elastomers mounted on the absorbent mass. In this embodiment, the elastomers are positioned in shoulders located at the ends of the absorbent mass and the volume of the latter is reduced relative to the elastomers positioned there. The stressing mechanism requires the insertion of a disc mounted close to the shoulder to make it possible during the displacement of the disc towards the shoulder to pressurise the part of the elastomer which passes beyond the shoulder. However, such a system is flawed not only in that it generates an interfering torsional or shearing stress of the disc against the elastomer, but also on the one hand forces the positioning of the elastomers at the ends of the absorbent mass and, on the other hand, causes an interfering pinching of the elastomer which reduces the effectiveness of the compression. The interfering pinching relates to the part of the elastomer which passes beyond the shoulder and is easily pinched between the disc and the end of the absorbent mass.